Leaching S from Pressure Acid Leaching Residue of Zinc Concentrate: Paraments Optimization Using Response Surface Methodology

The pressure acid leaching residue of zinc concentrate contains large quantity of sulfur. The present study attempts to leach sulfur using a mixture of ammonium sulfide and water solution at 25. Effects of three leaching variables: ammonium sulfide concentration, leaching time, liquid to solid ratio on the sulfur leaching rate were investigated. The process conditions were optimized using response surface methodology based on the central composite design. From the analysis of variance (ANOVA), the significant factors on response were identified. The optimum conditions for leaching elemental sulfur from pressure acid leaching residue of zinc concentrate were obtained by using ammonium sulfide concentration of 2.5mol/L, leaching liquid-solid ratio of 6.5:1 and leaching time of 7 min. Under the optimum experimental conditions, a maximum of 98.50% of sulfur was extracted. The experimental results obtained agreed satisfactorily with the model predictions, with a correlation coefficient (R2) of 0.99.